1. Field
Embodiments of the present disclosure relate to the structure of a stator for an alternating current (AC) motor, which is capable of improving the performance of the AC motor and also improving the manufacturing efficiency thereof.
2. Description of the Related Art
An alternating current (AC) motor is relatively inexpensive and has a long mechanical life, and therefore has been employed in various fields, for example, as a driving unit for a compressor of a freezing cycle in a refrigerator or an air-conditioner.
The AC motor includes a stator and a rotor. Upon application of electric power to the stator, the rotor is rotated by electromagnetic interaction between the stator and the rotor, thereby converting electric energy into mechanical energy.
The stator is constituted by a stator core, and a coil mounted to the stator core. FIG. 1 is a plan view showing a conventional stator core.
As shown in FIG. 1, the stator core 1 of the AC motor is structured by a plurality of silicon steel plates 2 all having the same ring shape while being stacked in a plurality of layers along the length of the stator core 1.
The stator core 1 includes a rotor receiving hole 1a centrally formed through the stator core 1 to receive a rotor, and a plurality of slots 1b arranged around the rotor receiving hole 1a to receive coils (not shown), respectively. A tooth member 1c is formed in a radial direction between the respective neighboring slots 1b so that the coil is wound on each tooth member 1c and thereby forms a magnetic path. The coil is inserted in the slot 1b through a gap 1d formed on an inner circumference between the respective neighboring tooth members 1c in a direction from the rotor receiving hole 1a. 
As a width of the gap 1d is decreased, core loss and excitation current are reduced, thereby improving the performance of the AC motor. However, according to the conventional structure of the stator core 1 as described above, the coil is inserted in the slot 1b through the gap 1d formed between the tooth members 1c. Therefore, the width of the gap 1d needs to be sufficient for insertion the coil, that is, about at least 1.70 mm in consideration of thickness of the coil.
In order to construct the stator of the conventional AC motor, first, a plurality of the silicon steel plates 2 are connected in a stacked manner, thereby forming the stator core 1. In a state where an insulator (not shown) is mounted at an inner wall of each of the slots 1b, the coil is inserted in the slot 1b. 
When the coil is inserted in the slot 1b, the coil cannot be wound directly on the tooth member 1c because the width of the gap 1d is too narrow. Therefore, the coil is rolled into a ring shape in advance at the outside of the stator core 1 and then is inserted in the slot 1b through the gap 1d. According to such a conventional method, installation of the coil is complicated. As a result, manufacturing of the stator becomes inconvenient.
In order to solve such inconvenience, the gap 1d may be widened so that the coil is directly wound on the stator core 1. However, core loss and excitation current will be increased in this case, thereby deteriorating the performance of the AC motor.
Furthermore, after the coils are mounted at the stator core 1, a coil trimming process is additionally performed in a manner that the coils drawn along the length of the stator core 1 and exposed out of the slot 1b are tied up using a fixing string, thus completing manufacturing of the conventional AC motor stator. As described so far, manufacture of the conventional AC motor stator has several inconveniences, for example, the coil trimming process additionally required after mounting of the coil.